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nervous system Flashcards

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Biology 101 flashcards
1
Q

what are the parts of the nervous system?

A

central and peripheral

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2
Q

describe the central nervous system

A
  • made up of the brain and spinal cord
  • Integrates and processes information
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3
Q

describe the peripheral nervous system

A
  • peripheral nerves
  • Carry messages to and from the central nervous
    system
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4
Q

what is the somatic nervous system?

A
  • voluntary control
  • connects to skeletal muscles
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5
Q

what is the autonomic nervous system?

A
  • involuntary control
  • connects to smooth muscles and glands, internal organs
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6
Q

what are the two divisions of the autonomic nervous system?

A

sympathetic and parasympathetic

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7
Q

What is a sympathetic response?

A

Fight or flight

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8
Q

What is a parasympathetic response?

A

associated with rest

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9
Q

Describe neurons

A
  • Basic structural and functional unit
  • Respond to physical and chemical stimuli
  • Conduct electrochemical signals
  • Release chemicals that regulate body processes
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10
Q

What are glial cells?

A
  • support neurons by
    • Nourish neurons, remove wastes, immune defence, supporting framework
  • About ½ the volume of the nervous system
  • Outnumber neurons 10 to 1
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11
Q

what are nerves?

A
  • bundles of neurons
  • surrounded by protective connective tissue
  • carry messages/signals throughout the body
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12
Q

What are the three types of neurons?

A

sensory, interneurons, motor

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13
Q

what do sensory neurons do?

A

gather info from sensory receptors and transmit impulses to CNS

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14
Q

what are interneurons?

A
  • found in the CNS
  • link between sensory and motor neurons
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15
Q

What do motor neurons do?

A

transmit information from CNS to muscles, glands and organs (effectors)

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16
Q

Draw the nerve impulse pathway

A

effectors <—— motor neurons <—– Interneurons <—– sensory neurons <—— Sensory receptors

17
Q

What is a reflex?

A
  • used in emergency situations
  • sudden, involuntary response
18
Q

What is a reflex arc?

A
  • simple connections of the neurons
  • very few neurons involved
  • signal to move effector comes directly from the interneurons in the CNS (brain or spinal cord)
  • no voluntary control involved
19
Q

What are the four basic parts of all neurons?

A
  • dendrites
  • cell boy (soma)
  • axon
  • branching ends
20
Q

what are dendrites?

A
  • receive impulses/signals
  • short branches
21
Q

what is the cell body?

A
  • contains nucleus
  • processes information from dendrite
    • signal only proceeds beyond the cell body if the signal is strong enough
  • contains metabolic reactions for cell
22
Q

What is the axon?

A
  • only one
  • conducts impulses away from the cell body
  • vary greatly in length (1mm to 1 m)
23
Q

what are the axon branches/terminal fibres?

A
  • chemical signals released from here
  • communicate with other nerves or effectors such as muscles
24
Q

What is the myelin sheath?

A
  • fatty, insulating layer on some axons
  • protects neuron
    increases speed of nerve impulse transmission
  • formed by Schwann cells (a type of glial cell)
25
Q

What are the nodes of Ranvier?

A
  • gaps in Myelin Sheath
  • where action potentials occur
26
Q

what are the three basic stages to nerve transmission?

A
  1. resting membrane potential - the relative charge inside of a resting neuron, contains potential energy
  2. membrane depolarization - occurs when membrane is excited, this is when a stimulus is transmitted
  3. membrane repolarization - the process of a neuron returning to resting membrane potential
27
Q

describe resting membrane potential

A
  • a neuron at rest is more negative inside than on the outside
  • caused by a greater consentration of positive ions outside the membrane of the neuron
  • charge separation is a form of potential energy “membrane potential”
  • approximately -70mv
28
Q

why is it is -70mv?

A
  • potential energy provides energy for generation of nerve impulse
  • larger number means a certain degree of stimulus is needed to create an impulse
29
Q

describe polarization

A
  • process of generating resting membrane potential
  • there is already a tendency for a neuron to be more negative inside because of:
    • large negative protein molecules in cell cannot get out
    • membrane nearly impermeable to some negative ions
  • very important contributor to the charge difference, as well as the way a neuron restores membrane potential is the sodium-potassium pump
  • potassium diffuses out of the cell faster than sodium diffuses in because of gated protein channels
30
Q

What is the sodium-potassium pump?

A
  • uses ATP to transport sodium out and potassium into the cell
  • three sodium ions are pumped out for every two potassium pumped in
  • potassium ions diffuse out of the cell more easily than sodium ions diffuse in (because of gated channels for potassium)
  • result is more positive outside and more negative inside
31
Q

describe membrane depolarization

A
  • when the nerve cell is excited, the membrane depolarizes
  • the membrane’s polarity changes, sodium channels open, sodium rushes in, potassium gates close
  • the positive ions. flowing in causes a charge reversal to + 40 mv
  • once the charge becomes positive the sodium gates close, potassium gates open, eventually restoring the charge to -70mv (but the sodium and potassium excess is inside)
32
Q

what is the threshold potential?

A
  • Charge that must be reached before a
    stimulus will result in a nerve impulse
  • About -55mv in most, but not all neurons
  • Any change to less than -55mv (between -
    70mv and -55mv) will have no effect
  • This is why a neuron response is
    sometimes called “all or none”
33
Q

What is action potential

A
  • charge reached above threshold potential
  • a nerve transmission begins or continues
34
Q

describe membrane repolarization

A
  • The Na+/K+ pump restores the ion
    concentrations inside and outside the cell
  • During the repolarization, the nerve cannot
    be reactivated – called the refractory
    period (1 to 10 ms) – this is a recovery
    time for the neuron
  • The pump requires ATP in order to
    operate
35
Q

describe the movement of action potential

A
  • the action in the neuron adjacent to an area of resting membrane causes that area to depolarize, moving the action potential along ( due to attraction of opposite charges)
  • since the area from which the action potential came in is still in recovery, the action potential will only move in one direction
36
Q

what can an action potential stronger response result from?

A
  • increased frequency of the neuronal firing is (not speed, which is constant for each neuron)
  • the number of neurons that respond to that level of stimulus (neurons may have different thresholds)
37
Q

What is the refractory period?

A
  • period after an action potential when a new impulse cannot be created
  • voltage gated sodium channels have not recovered and are not able to be opened at this point
38
Q

What is the role of the myelin sheath in the nodes of ranvier?

A
  • a nerve impulse travels much faster in a myelinated neuron
  • the insulating properties of myelin mean action potential can only occur at the noded of ranvier
  • result is less membrane needs to go through depolarization

bio 30 (20 decks)

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